SOLUTION: A semicircular window of radius 12 inches is to be laminated with a sunblck coating that costs $0.75 per square inch to apply. What is the total cost of coating the window, to the

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: A semicircular window of radius 12 inches is to be laminated with a sunblck coating that costs $0.75 per square inch to apply. What is the total cost of coating the window, to the       Log On

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Question 193226: A semicircular window of radius 12 inches is to be laminated with a sunblck coating that costs $0.75 per square inch to apply. What is the total cost of coating the window, to the nearest cent? (use n=3.24,Hint: Area of circle: A=nr^2)
Answer by MathGuyJoe(20) About Me  (Show Source):
You can put this solution on YOUR website!
Since the area of a circle is +A+=+pi%2Ar%5E2+, the area of a semi-circle is half that, or +%28pi%2Ar%5E2%29+%2F+2+.
In this case, the radius (r) of the semi-circle is 12 in. Substituting in we get:
+A+=+%28pi+%2A+12%5E2%29+%2F+2+ sq. in.
Simplifying gives us:
+A+=+%28144%2Api+%2F+2%29+ sq. in., or +A+=+72%2Api+ sq. in.
Substituting 3.14 in for pi gives us:
+A+=+226.08+ sq. in.
This is the window's area, in square inches. Multiplying this by the laminate's price per square inch gives you a cost of:
226.08 * $0.75 = $169.56


Hope this helps,


~ Joe